Github user cloud-fan commented on a diff in the pull request:
https://github.com/apache/spark/pull/16696#discussion_r99838684
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/basicLogicalOperators.scala
---
@@ -727,37 +728,18 @@ case class GlobalLimit(limitExpr: Expression, child:
LogicalPlan) extends UnaryN
}
override def computeStats(conf: CatalystConf): Statistics = {
val limit = limitExpr.eval().asInstanceOf[Int]
- val sizeInBytes = if (limit == 0) {
- // sizeInBytes can't be zero, or sizeInBytes of BinaryNode will also
be zero
- // (product of children).
- 1
- } else {
- (limit: Long) * output.map(a => a.dataType.defaultSize).sum
- }
- child.stats(conf).copy(sizeInBytes = sizeInBytes)
+ val childStats = child.stats(conf)
+ // Don't propagate column stats, because we don't know the
distribution after a limit operation
+ Statistics(
+ sizeInBytes = EstimationUtils.getOutputSize(output, limit,
childStats.attributeStats),
+ rowCount = Some(limit),
--- End diff --
This is a good point, maybe we should still separate the stats calculation
of `GlobalLimit` and `LocalLimit`.
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at [email protected] or file a JIRA ticket
with INFRA.
---
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
